Car-bottom furnace



Dec. 18, 1945. F, LOFTUS ETAL CAR-BOTTOM FURNACE Filed Aug. 21, 1943 2Sheets-Sheet 2 lNVENTORS firm It arrus Mme-Mr R. Tnoauquz BY PatentedDec. 18, 1945 NI TED ,STAT ES PATE N T FF 1 CE CAR-BGTTOM FURNACE FredH. Loftus, Mount Lebanon, :and Vincent :R.

Tro-glione, Wilkinsburg, Pa.; said Troglioneas- Signor to LoftusEngineering Corporation, Inc, 7

Pittsburgh, Pa e. corporation of Delaware Application August-21, 1943,Serial *No. 499,466 .2 Claims. (01.104-165) Bur invention relates toindustrial furnaces for heating, orannealing, or heat treating metalcastings, or other articles formed of other materials. The inventionisparticu'larly, though not exclusively, designed for oar-bottomfurnaces, and in such association it will be described.

A furnace of the sort in mind comprises a furnace chamber constructed ofrefractory brickwork, externally rein-forced and tied by means ofstructural steel and tie-rods. The "floor portion of the furnace, uponwhich the articles to be heated are borne, comprises the body of a car--a car that may be likened to a railroad fiat-car, whose floor isconstructed of refractory blocks.

.car is adapted to travel on wheels or rollers between service positionwithin the furnace, and loading and unloading position externallythereof. The front wall of the 'furnace is provided with a door which isopened and .closed, as :need be, to permit of the said movement of thecar into and out of the furnace, and, when the furnace contains itscharge, thedoor issealed shut.

In normal operation of the furnace, fuel and air are projected inregulatod "quantities "into the furnaceichamber, maintaining combustiontherein and heating to desired temperaturethe-articles to heztreated.The products of combustion fined escape through suitable outgo portsthat open through the walls of the i urnace chamber and communicatethrough suitable fiues to a stack or other vent. After the work has"been heated at regulated rate to the required temperature, thecombustion 'within the furnace is retarded or interrnpted'and the workallowed to-cool through a specified cooling cycle.

.As indicated above, the upper surface of the car body provides thework-bearing floor .portionzofathe furnace-chamber. Means are providedfor sealing the car body along its two sides and inner orlback end 5120the two side walls and back wail cfithe ifurnace chamber, while the doorof the furnace is sealed to the front wall of the furnace -.chamber :andto the outer or front :end of the car body. illhe art is "familiar withthe structure andiorganization of sand seals for this purpose. Asorganized within the closed furnace, the dandy .of the :car'is in effect'integrally united with theiurnace walls,2pro.viding.afurnace-chamherrin which the desired conditionsof combustion and thermalhead may .be established and main tained.

In order to facilitate the loading :and unloading of :the furnacecharge, the car that; :forms the worlebearing floor of the furnace .ismoved in linear path out of the furnace chamber, into a position wherethe work is accessible to an-overhead crane, or other work-handlingequipment.

Various mechanisms have been proposed and used for moving the carbetween said position of service within the furnace and said loading andunloading position externally thereof, and it will be understood thatour invention is directed to new and useful improvements in suchmechanisms.

One type of car-shifting mechanism hitherto in use consists in a cableanchored at one end to the front end-of the car and extending therefromto a sheave spaced from the front of the furnace by an intervalexceeding the length of the car. The outer end of the cable, trainedover said sheave, is oonnected'to a crane, which, by pulling the cable,draws the car out of the furnace. In order to move the oar back into thefurnace, one end of a second cable is .anchored to the inner end of thecar, whence it extends over a sheave journaled beneath the car at theinner end of the furnace, .and from :such sheave extends the length ofthe furnace to another sheave that is spaced from :the front of thefurnace, after the manner of the first-memtioned sheave. The crane isconnected to ithe outer end of this second cable, and tension applied tothe cable is effective toipull the'car into the furnace. In-a :moreelaborate form of this mechanism, the sheaves spaced from the front'ofthe furnace arereplaced'bya motor-driven drum, upon which the otherwisefree ends of'theicables are wound, one cable being wound in opposite.direction to theothenwherebyby rotating the drum one cable is paid out,:and .an equal length .of 113116 other rolled in, :effecting the travel.of z'the car. Rotation of :the drum in .one direction moves the caroutward from :the :furnace, and :rotation in opposite direction movesthe [car inward into the furnace. While a .mechanism.of thislsortxiseffective :in its intended capacity, it is open to certain objections,among :which may ;-be noted: The sheave and cable within the furnace areexposed (particularly when the .car .-is withdrawn from the furnace") tothe harmful effect .of the heat :developed within Ethe furnace andradiated from the hot furnace walls. Additionally, the floorspace inlfrontzof :the furnace is obstructed, obviously anobjectionablecircumstance.

Another car-shifting unechanism comprises :a toothed :rack secured uponthe :bottom of the car and extending longitudinally thereof. At thefront of the iurnaoe .a .gear-apinion meshes with the teeth of such rackandamotor'is conengaged by the gear-pinion, whereby rotation of thefurnace, and is is the pinion is adapted to shift the car outward agreater distance than the length of the car body that forms thework-bearing floor'of the furnace, with the effect that the work-bearingfloor is moved clear of the furnace for accessibility to a crane orother car-loading and unloading ap paratus. anism is that the floorspace immediately in front of the furnace is obstructed by the outwardextending rack when the furnace is in normal operation.

The mechanism of our invention avoids objections of the natureindicated, and affords many advantages which will be apparent to thoseskilled in the art. A mechanism embodying the invention is illustratedin the accompanying drawings, in which:

- Fig. I is a fragmentary view in plan of the floor of a mill in frontof a car-bottom furnace (not shown) with which the mechanism isorganized. The mechanism is installed in a. pit in the mill floor, andappears in plan;

Fig. II is a view of the mechanism in side elevation, the pit and thefloor of the mill, together with the front end of the car-bottomfurnace, being shown in vertical section. on the plane 11-11 of Fig. I;

Fig. III is a wiring diagram;

, Fig. IVis a diagrammatic view, illustrating a modification in thestructural organization of the mechanism, and Fig. Y is a fragmentaryview, showing in side elevation and to larger scale a portion of the'underframe or chassis of the car, and indicating the manner in, which acertain roller chain is secured to the frame; and

Fig. VI is a view in bottom plan of the structure shown in Fig. V.

Referring to the drawings, the reference nu- 'meral 2 indicates the car(fragmentarily shown in Fig. II) which forms the work-bearing floor ofthe furnace 3. The front end of the furnace is provided with a'doorwaythat is normally closed .by a door 4. The door is provided at its loweredge with blades that nest in a sand seal 6 at the front or outer end ofthe car. In order to load and unload the work or furnace charge, thedoor 4 is raised into open position, and the car is moved outwardthrough the furnace doorway to a position where the car is entirelyremoved from the furnace. The car is in this case adapted to move onrails I, the car being equipped with railway wheels 8.

The mechanism for shifting the car 2 between its alternate positionscomprises a plurality of wheels spaced apart in the linear direction oftravel of the car. The wheels are connected to means for powerfullyrotating them, and the'car is provided with means that engage the wheelsin such manner that as the wheels are rotated the car is caused totravel. As shown in Figs. I and II, the pluralityof wheels comprises twotoothed wheels 9 and H). The two wheels are journaled in a pit ll formedinthe floor I2 in front of the The objection to this car shifting mechfurnace. The wheel-engaging means comprise a rack l3 mounted beneath andsecured to the frame ll of the car. The rack l3 extends from one end ofthe car to the other and on the longitudinal center-line thereof, andthe teeth of the wheels engage the rack.

An electric motor I5 is connected through a gear-box l6 and achain-drive IT to rotate the shaft on which toothed wheel 9 is mounted,and a chain-drive l8 interconnects the shaft of wheel 9 with the shaftof wheel I 0, so that the two wheels 9 and I9 when rotated will rotatein unison. A weighted roller I9 is arranged to keep slack out of thechain l8. The energizing circuit 25 (Fig. III) of motor includes acontroller 26 that is subject to push-button switches 21 and 28 andcontact arms 23 and 24 of a limit switch 20. The limit switch 'includesa screw 22 connected by a chain-drive 29 (Figs. I and II) to thedriveshaft of toothed wheel l0, A finger 2| engages the screw 22 as anut, and as the screw is rotated the finger is caused to traveltherealong.

When the car is tobe withdrawn from the furnace, the furnace door- 4 isopened and the pushbutton 21 is pressed, closing acircuit 30 through thethen closed contact arm 23'of limit switch 20; the closing of suchcircuit operates the controller 26 which closes the circuit'25and setsthe motor in rotation, rotating the wheels 9 and [9 counterclockwise(Fig. 11) and, by reason of the existing engagement of the wheel 9 withthe rack I3,

the car moves outward from the furnace. 'As the car moves outward fromthe furnace, the rack l3 advances into engagement with the toothed wheel[9 that is rotating in unison with wheel 9, and

thus it is that the car may be moved beyond the.

position where the remote end (right-hand end) of the rack is engaged bythe wheel ,9. The wheel 19 may be said to pick-up where the wheel 9leaves off. The car is moved through a, distance equal to the length ofthe rack passing through engagement with wheel 9, plus the distance be-vtween the wheels 9 and [0, plus the length of the rack that passesthrough engagement with the wheel). The broken lines 2a in Fig. IIindicate the position of the rear end of the car in its outermostposition. i

- r The switch 21, oncepressed, remains in circuit closing position andthe controller 26 holds the circuit 25 closed until the car reachesfully withdrawn position, whereupon the finger 2|, travelling inright-to-left direction (Fig. III) under the effect of the rotatingscrew 22, engages and swings the contact arm 23 into open position,thereby opening circuit and effecting; opera tion of controller 26 tode-energize the motor IS. The motor l5 immediately comes to rest, withthe car fully withdrawn from the furnace.

When the car is to'be returned to'service position in the furnace, thepush-button 28 is pressed, closing circuit 3i, through contact arm 24,which during the preceding right-to-left travel of the finger 2| movedinto circuit-closing position. Thereupon, the controller 26 effects theenergization of the motor 15 in alternate direction and the wheels 9 and[9 are driven in clockwise direction, moving the car into the furnace.As the car reaches full lentered position in the furnace, the finger 2|,then traveling in left-to-right di-' rection engages and swings contactarm 24 into open position. All movement of the mechanism is immediatelyarrested, with the car in proper position within the furnace. I

From the foregoing description, it will be understood that the intervalbetween the wheels 9 and I is less than the length of the rack I3, andit is by virtue of this feature that the wheel 9 may be locatedsubstantially beneath the door of the furnace, and that the distance tothe wheel l0 may be minimized, while affording maximum distance oftravel of the car or furnace floor portion that is to be moved into andout of the furnace chamber.

Of course, the organization of the car-shifting mechanism within the pitll permits the pit to be covered, as in fact it will be, with only theupper limb or edge of the wheel I0 extending above the exposed millfloor or surface I 2 in front of the furnace and over which the cartravels.

It is important to note that the rack I3 is toothed wheels 9 and I0comprise sprocket-wheels whose teeth engage the rollers of the chain,The roller-chain is secured in taut condition to the chassis [4 of thecar, the attachment being effected by means of blocks 32 linked to eachend of the chain and bolted to the car chassis. The body of the chainmay be spot-welded, or otherwise secured, to the chassis at desiredpoints intermediate of its length. In Figs. V and VI, the means forsecuring the chain at intermediate points are shown as angle clips 32awelded to intermediate links of the roller chain, and secured by meansof bolts 32b to the beam Id of the car chassis. A roller-chain soorganized affords many advantages over a machined gear-rack.

Fig. IV illustrates that two (or more) parallel toothed racks I31) andBe, or two lengths of roller-chain, may be arranged on the bottom of thecar or floor portion 212 to be moved. In such structure, toothed wheels9b, lb and H10, all positively driven, will be arranged to be engaged bythe racks successively as the car moves. The space between successivewheels is less than the effective length of the racks. Manifestly, bysuch arrangement of racks and driving wheels, maximum travel of the caror floor portion of the furnace may be obtained with minimum obstructionof the floor in front of the furnace.

Within the scope of the invention defined in the appended claims,certain modifications, refinements and elaborations will occur to thoseskilled in the art.

We claim as our invention:

1. In a furnace comprising a furnace body and a car movable through thefurnace doorway into formed of a length of roller-chain, and that theand out of the furnace chamber and subject to diiferent temperatureswhen in the furnace than out, said car having a chassis of metalsupporting a refractory deck that forms th floor of the furnace when thecar is positioned in said chamber, and means for moving the car into andout of the furnace chamber; the invention herein described in such meanscomprising a rectilinear length of flexible roller chain extendinglongitudinally of the car beneath said chassis and attached atspaced-apart points to the chassis, a sprocket wheel journaled beneaththe car adjacent to the furnace doorway and engaging said roller chain,and means for selectively driving said sprocket in alternate directionsof rotation,

whereby the car may be moved into and out of the furnace chamber.

2. In a furnace comprising a furnace body and a car movable through thefurnace doorway into and out of the furnace chamber, and subject todiiferent temperatures when in th furnace than out, said car having achassis of metal supporting a refractory deck that forms the floor ofthe furnace when the car is positioned in said chamher, and means formoving the car into and out of the furnace chamber; the invention hereindescribed in such means comprising a rectilinear length of flexibleroller chain extending longitudinally of the car beneath said chassisand attached at spaced-apart points to the chassis, a sprocket wheeljournaled beneath the plane of the surface over which said car travels,with the upper edge of the sprocket wheel extending above said surfaceand engaging said roller chain, and means arranged below said surfacefor selectively driving said sprocket in alternate directions ofrotation, whereby the car may be moved into and out of the furnacechamber.

3. The structure of the next preceding claim, and a second sprocketwheel journaled below said surface at an interval from the first and inalignment therewith, and adapted to engage said roller chain when thecar is moved out of the furnace chamber, and means for driving saidsecond wheel in synchronism with the first, whereby the two wheelssuccessively engaging said roller chain are adapted to move said carthrough a distance substantially exceeding the length of said rollerchain.

FRED H. LOFTUS. VINCENT R. TROGLIONE.

